Liquid level control



Jan. 19, 1960 M. A. GILMAN LIQUID LEVEL CONTROL BY/@5404A United States Patent O LIQUID-LEVEL CoNTnoL u Y Morris A. Gilman, chicago, nl. l Application March 10, 195s, serial No. 720,194

1 claim. (C1200-ss) This invention relates to a liquid level control, and is particularly concerned with means for automatically controlling the operation of a sumpror cistern pump.

l Pumps of thistype are operated intermittently, in accordance with the amount of water or other liquid accumulated. The switch is closed when the water reaches a Vhigh level to start the pump and opened to stop the pump when the low water level is reached.

' Vln accordance with my invention the switch housing is detachably clamped to the side of the pump housing. The contacter plate for closing the switch is held in open position by magnetic means that will not permit closing movement Yof the contactor plate until the water pressure on the bottom of the housing exceeds the magnetic force. When the water reaches the predetermined high level the switch is closed rapidly and remains closed until the low water level is reached. At the low level the magnetic ciruit is closed and the `switch remains open. Regardless of theV Water level the switch cannot flutter between open and closed positions.

The switch is not connected rdirectly to the wiring for the pump motor, but is connected in series through a coupler preferably mounted above the high water level. In case of trouble with either the switch or the pump, repairs can be made to one unit without disturbing the Other-.4., 4

'The structure by means of which the above and other advantages of the invention are attained will be described in the `following specification, taken in conjunctionV with the-accompanying drawing illustrating "a preferred embodiment of the invention, in which:

Fig. 1 is a side elevational view showing the liquid level control embodying the invention as applied to a pump seated on the bottom of a sum-p;

Fig. 2 is an enlarged cross sectional View showing the switch mechanism with the electrical circuit open; and Fig. 3 is an enlarged cross sectional view showing the Y switch mechanism with the electrical circuit closed.

Referring to the drawings, the reference numeral 1 indicates a sump in which a pump enclosed in a housing 2 is positioned. A switch housing 3 is detachably secured to the pump housing by a split clamp 4 having its base portions 5 rigidly secured to the pump housing 2. The wiring 6 extends from the pump motor through a watertight tting 7 in the top of pump housing 2 and is plugged into `a coupler 8 which connects it in series to the wiring 9 extending from the switch housing 3. Although the coupler 8 is watertight it is preferred to position it above the high water level. A watertight protective casing 10 extending from the coupler 8 to the switch housing 3 encloses wiring 9 to provide additional protection for it.

Plugging the wiring into coupler S instead of connecting the Wiring of the pump motor directly to the switch facilitates repairs or replacements in the event of trouble with either the switch `or the pump. When the clamp 4 is opened and the wiring 6 pulled out of its plugged connection with the coupler 8, either the pump 2 or the yswitch housing 3 may be removed without disturbing the other.

ICC

The switch housing 3 comprises an inverted cup-shaped member 11 having a top wall 12 and a depending cylindrical Wall .13. The bottom of the inverted cup-shaped member 11 is sealed against the entrance of water by a ilexible diaphragm 14 secured thereto in any suitable manner. The diaphragm is preferably made of neoprene, but may be made of any suitable material. In the illustrated embodiment the lower edge of the cylindrical wall 13 is provided with a bead 15 extending outwardly therefrom. The outer edge portion of the diaphragm is in the form 0f an upwardly curled lip 16 terminating in a bead 17 adapted to be interengaged with the bead 15 to hold the diaphragm in snug engagement with the wall 13 and to provide a watertight seal.

The top wall 12 of the cup-shaped member 11 has a centrally disposed aperture 18 which is provided with a fitting 19 through which the wiring 9 extends. The fitting 19 is preferably made of neoprene and seals the aperture 18 against the entrance of water, thus making the switch housing completely watertight. The lower end of the protective casing 10 is bonded to the tting 19.

The diaphragm 14 is protected by a cap 20. supported in spaced relationship to the switch housing by an annular frame member 21 comprising a cylindrical wall 22, a lateral offset 23 and a lower cylindrical wall 24 spaced laterally from the switch housing by the offset 23. The protective cap 20 is mounted on the cylindrical wall 24 which extends below the lower edge of the switch housing to space the bottom wall 25 of the cap '20 below the diaphragm 14. The bottom wall 25 is provided with a centrally disposed opening 26 in which a slotted grill 27 is mounted. The cross sectional area of the opening 26 is approximately the same as the surface area ofthe diaphragm 14 aligned therewith.

The cylindrical wall 13 of the switch housing is provided with a plurality of horizontally aligned inwardly extending lugs 28 intermediate its height to support a steel plate 29. A split ring 3 0 is positioned above the plate*29 to hold it in place. If desired, the lugs 28 and split ring 3d may be replaced by embossments struck inwardly from the cylindrical Wall 13. The manner in which the plate 29 is secured within the cup-shaped member 11 is not critical,

`but it is essential that the plate 29 be made of steel or some Vmaterial capable of forming part of a magnetic circuit.

The diaphragm 14 is provided on its upper surface with an upwardly extending lipped ange 31. The ange 31 engages the perimeter of a plate 32 positioned on the upper surface of the diaphragm and movable therewith. A stud 33, preferably made of brass or other non-magnetic material, rigidly secured to the plate 32 extends vertically upwardly into an aperture 34 in the steel plate 29. The plate 29 may be provided with a depending cylindrical skirt 35 contiguous to the aperture 34. The'top of stud 33 is provided with an axial threaded recess 36 for a purpose hereinafter described.

A magnet 37 positioned above the steel plate 29 is provided with a centrally disposed aperture 38 for receiving the shank of a screw 39. Screw 39 is preferably made of brass or other suitable non-magnetic material and is threaded to engage the thread of recess 36 to hold the magnet in rigid engagement with the stud 33 so that the magnet and the diaphragm plate 32 move together as a unit. A contacter plate 40 is mounted above the magnet 37. Preferably the magnet 37 is a ceramic magnet and no insulation is required between it and the contacting bar. If the magnet is metal, an insulating disk 41 separates the contacter plate 40 from the magnet. A fiber washer 42 is positioned between the head of screw 39 and the contactor plate. The magnet may also be provided with one or two guide pins 43 depending therefrom and extending Vsplaced'relationship toa contact button 4S with which itis alignedf A-lead wire 49, constituting part of the wiring,

9, is connected to each terminal plate 47.

The operationof the liquid level control ymaybe sum mariz'ed as follows. When the water level inthe sump is belowthe switch housing 3 the magnetic force'ofvmagnet 3.7holdsit in engagement withV the steel plate 29 Vand the electrical circuit remains open, as shown in Fig. 2.

Asthe water level rises, water-hows through the slotted grid `2.7 and exerts pressure against the bottomof the diaphragm 14. Since the position of the switch housing is Xed relative to the floor level, the pressure of the water against the bottom of the diaphragm increasesY as the water level rises. The magnetic orceis designed to hold the magnet against the steel plate until a predetermined pressure reached. The predetermined pressure is reached when the water reaches its high level, and the pressure against the diaphragm at that point is, greater than the magnetic force holding the magnet againstemovef ment upwardly from the steel plate- Accordingly, the water pressure forces the diaphragm upwardly and breaks the magnetic eldgthus causing the magnet to move upwardly very rapidly to establish contact between each contact button 45 and the opposite terminal contact button 43 to close the electrical circuit as shown in Fig. 3.

The pump is wired into the circuit in'series through'the coupler 8 and starts operating to pump -the water out of tween the magnet and theV steel plate is so great that no magnetic force is exerted toward opening they electric circuit.V Accordingly, the electrical circuit remains.

closed until the Water level recedes so far that `the water plate 29 to maintain the alignl '4. is opened. As the maget magnetic force pulls the magnet rapidly into contact with thersteel plate to hold the -electrical circuit open until the water rises again Yto the high water level.

While I have described a preferred embodiment of the inventionV in considerable detail, it will be understood that the description thereof isintended to be illustrative,

rather than restrictive, as many details of the .structure may be modie'd or changedv without departing from the spirit or scope of the appended` claim. Accordingly, I

do not desire to be restricted to the exact details of construction described.

I claim: p g

In combination, a switch housing having an opening therein, a pressure-responsive diaphragm closing saidY opening, a magnet within said housing in spaced relationship to said diaphragm, means connecting said magnet to said diaphragm to move said magnet in accordance with the movement of said diaphragm, a contacter secured to lsaid magnet and movable therewith, a platewrof ,magnetic material positioned intermediate saidmagnet pressure is too small to hold the diaphragm up against and said diaphragnninsulating material secured-to said plate, anda pair of terminal contacts mounted on said insulating material in spaced relationship to each other and to said contacter, saidmagnet being adapted to move said contactor into contact with said terminal contactsv upon applicationofpressureY tothe outersurface of said diaphragm when said pressure exceeds themagnetic` attraction between the magnet and the plate of magnetic material.

References Cited in they file of this patent UNITED STATES PATENTSA 2,302,250 Penn Nev. 17, 1942 2,353,740 Malone July 18,1944 2,514,630' Downing V July 11, 1950 2,598,556Y Judson May 27, 195.2 2,628,296 I 'Y 1953 2,716,525 1955 2,814,687 Forwald Nov. 26., Y19,57 2,847,528 v Combs Aug; 12, 1958 2,856,481 Ernst Qct. 14,1958

. FoRarGN PATENTS "533,119 Y Great Britain Feb. 7, 1941 571,125 Great Britain 'A ug,. 8,

approaches the steel plate, thev 

